Perfluoroalkylated ethenes containing only straight perfluorinated chains are known, notably, from the published work of G. Santini, M. LeBlanc and J. G. Riess, TETRAHEDRON 29, 2411 (1973), and of F. Jeanneaux, G. Santini, M. Le Blanc, A. Cambon and J. G. Riess, TETRAHEDRON 30, 4197 (1974). The prior art does not, to applicants' knowledge, record perfluoroalkylated ethenes containing branched fluorinated alkyl chains.
The use of perfluorinated or highly fluorinated compounds as oxygen carriers or respiratory gases in blood substitutes has previously been the subject of numerous articles. A review of this subject was published by J. G. Riess and M. Le Blanc in ANGEWANDTE CHEMIE, INTERNATIONAL EDITION IN ENGLISH, 17, 621-700 (1978).
For a blood substitute to be considered entirely satisfactory, it must simultaneously fulfill five conditions:
be obtainable in pure state and in a perfectly defined form; PA1 possess a high capacity for dissolving respiratory gases; PA1 be inert and atoxic; PA1 be capable of forming stable aqueous emulsions of oil in water type, with an average particle size of less than about 0.1 .mu.m, with no particle exceeding 0.6 .mu.m; PA1 be eliminable very rapidly from the organism.
None of the fluorinated carriers hitherto known fully satisfies all these conditions. The straight-chain bis-(perfluoroalkyl)-1,2-ethenes of the prior art, though already representing considerable progress from the purity standpoint, are always obtained in the form of mixtures of bis-cis- and trans-isomers, the latter being predominant. Thus, chromatographic analysis of the bis-(perfluoro-n-hexyl)-1,2-ethene or dihydro-7,8-perfluorotetradecene-7 shows that it contains 94.1% trans-isomer and 4.6% cis-isomer, the rest consisting mainly of the corresponding saturated derivative, bis-(perfluoro-n-hexyl)-1,2ethane. The cis- and trans-isomers of the straight chained bis-(perfluoroalkyl)-1,2-ethenes have boiling points so close together that it is difficult to separate the isomers by distillation. The differences in their boiling points are, however, distinct enough to entail differences in the rates of excretion of the isomers.